1. Field of the Invention
The present invention relates to a surgical instrument especially for minimally invasive surgery having a distal instrument head moveably connected to an instrument or tube shaft.
2. Discussion of the Prior Art
For example, from DE 100 36 108, a surgical instrument of this kind is known. It substantially consists of a tube or instrument shaft at the one proximal end of which an instrument handle is arranged for the operation of an instrument head disposed at the opposed distal end of the tube shaft via a transmission path. The instrument head can be bent, or rather inclined with respect to the tube shaft and, moreover, holds an effector rotatably supported in the instrument head in the form of a type of forceps or tongs, one jaw of which is pivotably supported on the effector and is likewise operable by means of the instrument handle.
In more concrete terms, the transmission enables at least a first movement of the instrument handle, according to this prior art to be triggered by rotation of an operator's hand, to be transformed into a rotation of the effector at a predetermined transmission ratio with respect to this operating movement. This makes it possible to rotate the effector despite the relatively restricted possibility of motion of a human hand about up to 300°, for instance, and, thus, to realize complex motions without changing the grip at the handle. Moreover, a second movement of the instrument handle, for instance, bending the same with respect to the tube shaft, is converted into an inclination movement of the instrument head.
The transmission provided inside the instrument handle and the tube shaft is designed such that a most largely decoupled operation of each individual movement of the instrument head and the effector is permitted. However, such a transmission is necessarily extremely complex and consequently also requires sufficient assembly space. Moreover, a complete decoupling of the individual movements is not completely ensured.
In WO 2009/001 497 A2 another surgical instrument is disclosed comprising an instrument handle, an instrument shaft having a distal end and a proximal end at which the handle is connected and an instrument head, pivotally linked to the distal end of the instrument shaft. The instrument head comprises an effector rotatably supported in the instrument head around its longitudinal axis as well as a surgical tool held by the effector. A mechanical transmission system is provided at least partially within the instrument shaft transmitting and/or converting mechanical operation signals from the handle to the instrument head at least for pivoting and/or rotating motions. Finally, a bending flexible as well as torsional rigid, hollow spindle is interconnected in the transmission system bypassing the hinge and directly connecting the effector with the mechanical transmission system for transmitting at least rotating signals from the handle to the effector. Here, the bending flexible as well as torsional rigid, hollow spindle is a spiral spring, which is mounted on its one end to an rotating tube shaft at least rotatably supported within the instrument shaft as a member of said transmission system.
In view of this prior art, it is an object of the present invention, to provide a surgical instrument of this generic type in which motions of an instrument head as well as of an effector can be performed using a transmission having a simple design especially in the area of the instrument head. Another target of the invention is, to provide free space especially in the area of the instrument head by simplifying the design of the transmission which space can be used for applying additional functions to the surgical instrument which are useful for surgical treatment. A further target of the invention is to provide a surgical instrument adapted for single port surgery according to the common definition in the field of minimal invasive surgery.